That's what I've read here on CC.
I usually they to keep my balance somewhere around $10 to be billed to my credit card so when I went to get the port charge refunded it only amounted to $10 and change when totaled out between my husband & I.
We also missed another port, Aruba, which was replaced by Curaçao. I guess the charges were identical so I assumed the port charges were either identical, although if so, they didn't charge or refund us the difference.